Sorry for coming off like a jerk, but the fact is that it is impossible to know what would need to be done to swap things the way you are thinking, because it hasnt been done. Purpose built race cars have been built using bare bodies and whatever motor the builder was using (usually not a stock 4.6) but as far as taking apart an S197 and making a frankenstein...not so much.
There are TONS and TONS of electronics in these cars that would have to be addressed, plus the chassis is completely different from the 79-04 cars that pretty much established the Mustang as the great performance car that it is. There has been plenty of time for people to figure out all the different things that can be changed and modified...people are still trying to figure out what can or cant be done with these new stangs.
I guess if there is something constructive that you can get from my previous posts, it is that the reason I make it sound like a "Duh, why the F would you even think that" situation is because there is just SO much that would need to be done to make it work that it really doesnt make sense.
The 05's can be had for some very attractive prices these days...and are a whole lot of fun to drive and can be hopped up really good...use aftermarket parts to gain horsepower, dont worry yourself with a motor swap. If it was an old fox body with a 4cyl that you wanted to swap a 5.0 into then by all means...but the new ones are just too involved